1. Field of the Invention
The present invention relates to an ink tank, a recording head, and a package including the ink tank and the recording head in a distribution form.
2. Description of the Related Art
As a well-known type of recording apparatus for recording on recording media, such as paper, cloth, plastic sheet, or sheet for OHP (hereafter collectively referred to simply as recording paper), there is the ink jet type recording apparatus each provided with a recording head.
The ink jet type recording apparatus has been commercialized and is widely used as output units of information processing equipment, such as printers at the output terminal of copying machines, facsimiles, electronic typewriters, word processors, and work stations. Moreover, the ink jet recording apparatus is available on the market as hand-held or portable printers for personal computers, host computers, optical disk devices, video devices, etc.
There have been proposed various kinds of ink discharge methods in the ink jet recording head, among which the recording head that discharges the ink by a thermal energy conversion element is advantageous in that discharge nozzles can be arranged with high density and the size of the recording head itself can be reduced easily. Additional advantages of this recording head are that it is possible to make full use of the merits of integrated circuit (IC) technology and micro-fabrication technology in the semiconductor sector, and that the ease of high-density packaging reduces production cost.
In consumer printers, the ink tank for storing ink to be supplied to the recording head, is replaced with a new ink tank when it becomes empty. The ink tank is structured such that the user can easily change ink tanks. Even with an ink cartridge which is a unified body of a recording head and an ink tank, the ink tank is replaced with a new one when the ink is consumed.
To take an example of a detachable ink tank, one which is disclosed in Japanese Patent Application Laid-Open No. 11-348308 (corresponding to U.S. Pat. No. 5,278,584) is known. The ink tank described in Japanese Patent Application Laid-Open No. 11-348308 includes a data storage medium for storing information about ink stored in it. More specifically, the substrate attached to the ink tank has an electric circuit including memory elements and electric contacts thereon, and various items of information about stored ink are written on the memory elements. Therefore, the recording apparatus with the ink tank mounted on it reads stored information and performs recording based on read information to obtain proper record output.
Incidentally, an ink tank detachable from a device such as mentioned above or a single unified cartridge of a recording head and ink tanks, after being shipped from the manufacturer and following the distribution process until they are used, are left in distribution-purpose packages. As for the form of package, ink tanks or cartridges are mostly contained in tightly-sealed packages. Depending on the physical distribution environment, the solvent components may evaporate from the ink of ink tanks or cartridges packed in packages.
Japanese Patent Application Laid-Open Nos. 11-170554 (corresponding to U.S. Pat. No. 6,706,349) and 2001-348053 disclose that an amount of ink evaporation can be minimized by enhancing the sealing performance of packages. According to Japanese Patent Application Laid-Open Nos. 11-170554 and 2001-348053, if the amount of evaporation of ink components from the ink tank can be reduced, changes in ink characteristics (change in ink components, for example) can be prevented. If the sealing performance is improved, even though the ink leaks from the ink tank, the leaked ink can be prevented from spilling out. If spillage of ink can be prevented, it is possible to prevent the leaked ink from staining the user or the equipment.
Though a continuous evaporation of ink components can be prevented by a tightly-sealed structure of a package, the ink components are saturated in the package. On the other hand, with regard to ink tanks without electric circuits, such as memory elements, no problem is observed. However, with ink tanks fitted with an electric circuit or with a recording head which naturally includes electric circuits, the ink components which are saturated in the packages can damage the electric circuits when they are contained in packages.
For example, there is ammonia among the components that evaporates from the ink, and ammonia reacts with materials, such as wires of the electric circuits of the ink tanks or copper used in electric contacts. If the package is tightly-sealed, because ammonia gas is not discharged out of the package, the ammonia gas reacts with many of the wires and electric contacts. As a result, corrosion can develop at the wires and the electric contacts used on the substrate attached to the ink tank or the recording head.
As a countermeasure against corrosion, it is considered to remove ammonia gas liberated in the tightly-sealed structure of a package by some means. However, depending on the amount of ammonia to be removed, there is a possibility that the components of the ink contained in the ink tank may change. If the ink components should change, it is feared that recording results, such as printing quality, are affected.